International Workshop ' Complex study of the state and climate variability of the East Siberian sector of Arctic ', CITES, Siberian Center for Environment Research and Training.
Tomsk, Russia, June 26-30, 2015
FROM FRESH- TO MARINE WATERS: THE FATE OF DISSOLVED ORGANIC MATTER IN THE LENA DELTA REGION, SIBERIA
Rafael Gonçalves-Araujo1, Colin Stedmon2, Birgit Heim3, Ivan Dubinenkov4, Alexandra Kraberg5 , Denis Moiseev6 and Astrid Bracher7
1Alfred Wegener Institute, Bussestraße 24, 27570 Bremerhaven, Germany. rafael.goncalves.araujo@awi.de.
2Technical University of Denmark, Kavalergården 6, 2920 Charlottenlund, Denmark. cost@aqua.dtu.dk.
3Alfred Wegener Institute, Telegrafenberg A43, 14473 Potsdam, Germany. birgit.heim@awi.de.
4Alfred Wegener Institute, Am Handelshafen 12, C-219, 27570 Bremerhaven, Germany. ivan.dubinenkov@awi.de.
5Alfred Wegener Institute, Kurpromenade, C-33, D-27498 Helgoland, Germany. alexandra.kraberg@awi.de.
6Murmansk Marine Biological Institute, Vladimirskaya 17, 183010 Murmansk, Russia. denis_moiseev@mail.ru.
7Alfred Wegener Institute, Bussestraße 24, 27570 Bremerhaven, Germany. astrid.bracher@awi.de.
Preferred presentation type: Oral
The connectivity between the terrestrial and marine environment in the Artic is changing as a result of climate change. This is influencing both freshwater budgets and the supply of carbon to sea. This study characterizes the composition of dissolved organic matter (DOM) within the Lena Delta region across the fresh water-marine gradient. Six fluorescent components (four humic-like; one marine humic-like; one protein-like) were identified by Parallel Factor Analysis, with a clear dominance of humic-like signals in fresh waters. At higher salinities there was an increased autochthonous contribution. Colored DOM (CDOM) and dissolved organic carbon (DOC) were highly correlated and, as a response to the hydrographical forcing, the region displayed a pseudo-conservative behavior of DOM in relation to salinity at marine-influenced sites; and a non-conservative behavior with evidence of considerable removal of DOM (up to 54%), likely driven by photodegradation and sorption/flocculation, at sites influenced by the Lena River plume. The latter mixing curve was split into three mixing regimes with regard to different amount and reactivity degree of DOM and to the factors driving DOM variability: 1) the low salinity regime (salinity>10) with high concentrations of DOM, dominated by highly reactive terrigenous contribution and characterized by rapid removal; 2) the intermediate regime (10<salinity<25) exhibiting lower concentrations of DOM and a decreased contribution and reactivity of terrigenous compounds; and 3) the high salinity regime (salinity>25) showing the lowest DOM and an increased contribution of less reactive compounds, displaying a pseudo-conservative behavior, with relatively low removal/addition processes controlling the dilution of DOM.
